International Appliance Manufacturing 2008 - (Page 75) A Sound diAgnoSiS At the Owens Corning Acoustic Research Center, microphones are arrayed around an appliance to test noise levels. f a robotic vacuum cleaner works while no one is home, does it still make a sound? That new spin on the tree falling in the forest may not inspire you to a night course in philosophy, but it does underscore an important point in the realm of sound quality: there is a distinction between the objective reality and the subjective experience. The former relates to the physical phenomenon of generating sound pressure waves that can be quantified and characterized by a variety of standard metrics such as intensity level, frequency, harmonics, and so on. This objective aspect is often referred to as noise. The subjective aspect, by contrast, is fuzzier in nature as it relates to how people perceive and react to what they’re hearing. This aspect is typically referred to as sound. The distinction is important to understanding that improving sound quality is not just about making things quieter. To some, a dripping faucet can be more intrusive than the jet engine noise from an airplane overhead. Sometimes a product’s sound quality can be I improved by changing its character without actually lowering its noise level. For product designers lacking expertise in this area, the whole field can seem like a black art combining physics and psychology, math and magic. But such a designer need not be intimidated; there are many good acoustical consultants and testing laboratories that can lead the designer through that murky territory. A good acoustic testing lab can provide a detailed characterization of a product’s sound, identify the various sources of sound in the different phases of the product’s operation, suggest some remedies for altering or quieting the sound, and even help determine whether or not the sound warrants any design attention. Over the years, many product manufacturers have sought help from Richard Lyon, an acoustic expert with more than 30 years of experience and founder of R.H. Lyon Corp. of Belmont, Mass. One of the companies who turned to Lyon for help in dealing with noise and sound issues was a maker of Labs help identify and locate noise sources. by larry adams International Appliance Manufacturing 2008 75
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